Hydrazide Crosslinker for Aqueous Pressure-Sensitive Adhesive
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Solution Overview
Problem
Conventional epoxy-based and carbodiimide-based crosslinkers used in re-releasable pressure-sensitive adhesive compositions require a two-pack type formulation, are unstable in liquid form, and are sensitive to temperature, making it difficult to achieve stable performance, especially in cold conditions, and necessitate aging for proper crosslinking.
Innovation Solution
A re-releasable aqueous pressure-sensitive adhesive composition using a hydrazide-based crosslinker that is soluble in water, allowing for a one-pack type formulation without the need for aging, and combining it with specific emulsions [A] and [B] to form a pressure-sensitive adhesive layer with stable and rapid crosslinking properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epoxy-based or carbodiimide-based crosslinkers are used, then crosslinking can be achieved, but the composition requires a two-pack type formulation and aging, reducing ease of operation and productivity
Solution Approach 1:
The patent changes the chemical parameter of the crosslinker from epoxy-based or carbodiimide-based to hydrazide-based, which enables the composition to be formulated as a one-pack type without requiring aging. This parameter change maintains crosslinking reliability while significantly improving ease of operation and productivity
Solution Approach 2:
The patent extracts the crosslinker from a separate packaging requirement and incorporates it directly into the aqueous pressure-sensitive adhesive composition. By using a hydrazide-based crosslinker that is stable in aqueous environments, the crosslinker can be pre-mixed without premature reaction, eliminating the need for two-pack formulation and aging processes
2Reliability
If epoxy-based or carbodiimide-based crosslinkers are used, then crosslinking can proceed, but liquid stability deteriorates due to gelation and viscosity increase, reducing reliability
Solution Approach 1:
The patent changes the chemical nature of the crosslinker from epoxy-based or carbodiimide-based to hydrazide-based, which fundamentally alters the reaction characteristics. The hydrazide-based crosslinker maintains excellent liquid stability without causing gelation or viscosity increase, while still achieving reliable crosslinking function
Solution Approach 2:
The patent replaces unstable crosslinkers that cause premature reaction with a stable hydrazide-based crosslinker that remains dormant in the aqueous composition until application. This allows the composition to be stored and handled without degradation, improving liquid stability while maintaining crosslinking functionality
3Reliability
If conventional crosslinkers are used, then crosslinking can occur, but temperature sensitivity increases making performance unstable in cold conditions, reducing adaptability
Solution Approach 1:
The patent changes the chemical structure of the crosslinker to a hydrazide-based compound, which exhibits superior temperature tolerance compared to epoxy-based or carbodiimide-based crosslinkers. This parameter change enables stable crosslinking performance across a wide temperature range, including cold conditions, significantly improving adaptability while maintaining crosslinking capability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves stable pressure-sensitive adhesive properties at both initial and later stages with excellent re-releasability and environmental friendliness, eliminating the need for aging and improving workability across varying temperatures.
Implementation Method 1
a crosslinker [C] containing a hydrazide-based compound that is crosslinkable with a constituent unit of the emulsion [A] and soluble or dispersible in water
Data Source
AI summary
The present application provides a re-releasable aqueous pressure-sensitive adhesive composition containing: as a main component, an emulsion [A] of a (meth)acrylic acid-based ester copolymer, an emulsion [B] of a (meth)acrylic acid-based ester copolymer, and a crosslinker [C]. The emulsion [A] contains a constituent unit that has a carboxy group or a hydroxy group and reacts with a crosslinker. The emulsion [B] is included in the composition in an amount of 0.6 parts by mass or more in terms of a solid content based on 100 parts by mass of a solid content of the emulsion [A] and functions as a crosslinking assistant. The emulsion [B] has a peculiar structure dissolving in water upon neutralization and is unmeasurable in a particle diameter distribution analysis at pH from 6.5 to 7.5. The crosslinker [C] is a hydrazide-based compound that is soluble or dispersible in water.